The invention relates to the manufacture of transducers such as microphones, earphones, loudspeakers, probes for echography, hydrophones, etc. which comprise at least one active element comprising a polymer film fitted with electrodes. It relates more particularly to transducers in which one or more polymer films are shaped by thermoforming and/or electroforming, so as to obtain a self-supporting structure such as a dome, cone, etc. These shapes correspond to nondevelopable surfaces which are generally obtained from a simple or composite structure whose faces are metalized after shaping. In the case where the shaping generates considerable stretching of the polymer, for example during shaping of a flat film so as to obtain a self-supporting protuberance in the form of a spherical skullcap, there is established a mechanical anisotropy such that the shape obtained may tend to shrivel during subsequent metalization and polarization operations, which involve heating of the polymer. To get around this disadvantage, several molds are used for maintaining unchanged the shape obtained in all the steps of the process, which complicates the manufacturing equipment.
When the shaped polymer structure is to be provided on each face with electrodes which define adjacent active zones, difficulties are met with masking the zones surrounding these electrodes. In fact, the complex shape of the structure causes the patterns of the mask to be projected with distortions or, due to the existence of shadow zones, the masking introduces unacceptable electrode discontinuities.